Also changed the ts_ann field on statements to be an ann instead,
which explains most of the changes.
As well, got rid of the "warning: no type for expression" error
by filling in annotations for local decls in typeck (not sure whether
this was my fault or not).
Finally, in bitv, added a clone() function to copy a bit vector,
and fixed is_true, is_false, and to_str to not be nonsense.
It's still sketchy. I added a typestate annotation field to statements
tagged stmt_decl or stmt_expr, because a stmt_decl statement has a typestate
that's different from that of its child node. This necessitated trivial
changes to a bunch of other files all over to the compiler. I also added a
few small standard library functions, some of which I didn't actually end
up using but which I thought might be useful anyway.
